The present invention generally relates to an optical information recording and reproducing apparatus, and a method thereof for optically recording and reproducing operations information using an information recording medium divided into a sector unit of a fixed length.
In recent years, the use of information recording and reproducing apparatuses using information recording mediums for exchanging large amounts of information has spread. An optical disc apparatus records and reproduce information using extremely small pits on the optical disc with the use of laser light beams. As the amount of information to be recorded on one information recording medium increases, it becomes difficult to improve the reliability of data to be recorded on the information recording medium. Presently, when the quality of the data has deteriorated among the data recorded on the information recording medium, it is difficult to correctly reproduce the information. It is significant to be able to reliably detect data which possibly cannot be reproduced in the near future and to move the data into another region of the information recording medium while the reproducing operation can be correctly performed.
The conventional optical information recording and reproducing apparatus was provided with separate normal reproduction and verification reproduction. Assume that a small computer system interface (hereinafter referred to as SCSI) was provided on, for example, a host interface, and the respective reproducing operations were effected by the reception of a READ command for normal reproduction from the host computer and a VERIFY command for reproduction of the verification. The normal reproducing operation is used to reproduce data as correctly as possible even if the data to be recorded on the information recording medium has deteriorated. Factors causing deterioration of data include smaller signal amplitude, more noise components because of aging deterioration of the information recording medium, flaws, dust on the surfaces of the information recording medium, and non-optimum recording conditions. In the conventional optical information recording and reproducing apparatus, when reproducing conditions are not influenced by the deterioration of the data, the decision of whether the analog signal is a 0 or 1 was set as 50% of the data amplification in the slice level and the error correcting function was set to maximum. The verification reproducing operation guarantees the normal reproducing operation even if data recorded on the information recording medium has deteriorated. In the conventional optical information recording and reproducing apparatus, data likely to deteriorate was selected for verification reproduction. The decision of whether the analog signal is a 0 or 1 was set at 60% in the data amplification for the slice level and the error correcting function as one of the reproducing conditions to be likely influenced due to the deterioration of data was reduced to half of what is used in the normal reproducing conditions as the reproducing conditions to be likely to be influenced in the deterioration of the data.
The host computer is required to effect the following operation to detect the data which possibly can no longer be reproduced in the near future using the above described function provided with the conventional optical information recording and reproducing apparatus.
The host computer 1 issues a verification reproduction instruction (VERIFY command of the SCSI) with respect to a sector having recorded information. Data which possibly cannot be reproduced in the near future from the optical information recording and reproducing apparatus 2 can be detected, using verification by receiving the report that the reproduction verification is not effected. Then, a normal reproduction instruction (READ command of the SCSI) is issued and data which possibly can not be reproduced in the near future is retrieved. In order to rewrite the data on the information recording medium, the recording instruction (WRITE command of the SCSI or WRITE AND VERIFY command) is issued.
In order to detect data which possibly can not be reproduced in the near future, and to move the data to another region of the information recording medium during the correct reproducing operation, the conventional optical information recording and reproducing apparatus has to use both the reproduction instruction intended to verify and a reproduction instruction intended to reproduce the data.
As a result, the burden of the host computer increases and the processing time increases which lowers performance. Tracking and focusing cannot be shifted deliberately in verification reproduction. Because tracking and focusing cannot be shifted deliberately in the reproduction for verification, there is a problem of failing to detect a sector which will possibly deteriorate to a degree having little possibility of being correctly reproduced in the near future.